The present invention relates to easel hinges in general, and more particularly to hinges utilized for picture frame supports.
So-called easel hinges for joining the back surface of a picture frame to the top of a swingable support flap member are known, for example from U.S. Pat. Nos. 2,857,618; 3,994,045; 4,050,117 and 4,349,942. The U.S. Pat. No. 2,857,618 patent discloses a hinge construction in which pintles formed along an edge of one of the hinge leaves are caught within a triangularly-shaped socket formed along the edge of the other hinge leaf.
The U.S. Pat. No. 3,994,045 patent discloses an easel hinge including an outer hinge plate formed with a curled barrel at one end, and an inner hinged plate also provided with a curled barrel coaxial within the curled barrel of the outer hinge plate with both barrels curled in the same direction.
U.S. Pat. Nos. 4,050,117 and 4,349,942 both describe an easel hinge construction in which both barrels of two hinge plates are curled in the same direction.
In each of the above-discussed patents, stop means are provided on the hinge, which cause one hinge plate to stop in one or a plurality of angular positions relative to another hinge plate so as to spread apart the hinge plates and therefore pivot the support flap from the backing of the frame to permit the frame to stand in an open upright position.
The stop means of the hinge disclosed in the '618 patent is constructed as a friction catch which includes a first stop member engaging the pintle on the one leaf of the hinge to limit rotation of the hinge leaves relative to each other in one direction and a second stop member which engages the pintle in the one hinge leaf so as to limit relative rotation of that leaf in an opposite direction.
The stop means of the hinge described in U.S. Pat. Nos. 3,994,045; 4,050,117 and 4,349,942 is constructed by means of tangs or projections formed on one of the hinge leaves and cooperating, e.g. with edges of respective openings formed on another of the hinge leaves so as to provide for two independent and simultaneously acting stop means which ensure that a desired opening movement of the hinge leaves is securely limited.
It will be appreciated, however, that stop means utilized in all aforediscussed known hinge constructions require fairly high machining tolerances for manufacturing such hinges because not only the outer circumference of the curled barrel of the inner hinge leaf must closely fit within the inner periphery of the curled barrel of the outer hinge leaf to ensure steady rest positions but also all protruding parts of the hinge leaf, constituting the stop means must fit within the respective openings or recesses of the other hinge leaf.